ST. PETERSBURG — Beverly Weston lays things out plain and simple in August: Osage County. • "My wife takes pills and I drink. That's the bargain we've struck," says Weston, a poet and college professor, nursing a glass of whiskey, in the prologue of Tracy Letts' play about a dysfunctional family in Oklahoma. • Offstage, Beverly's wife, Violet Weston, can be heard cursing.

"I think it began beautifully," said Lisa McMillan, who plays Violet in the American Stage production that opens this weekend. Over lunch after a rehearsal, she was discussing the relationship between Violet and Beverly with the actor playing her husband, Michael Edwards.

"Yes, I think the two of them began as a classy family," Edwards said. "But then he had some fame as a poet, and that put them into a downward spiral that took the family with them. The whole family went into this tornado of destruction."

August: Osage County, set in an Oklahoma country house, turns on the disappearance of Beverly, who is later discovered to have committed suicide. The couple's three grown daughters come home, and an epic psychodrama unfolds over three acts lasting more than three hours.

Alcoholism and drug addiction are central to the play. During his opening monologue, Beverly enumerates a laundry list of his wife's pills.

"Valium. Vicodin. Darvon, Darvocet. Percodan, Percocet. Xanax for fun. OxyContin in a pinch. Some Black Mollies once, just to make sure I was still paying attention. And of course Dilaudid. I shouldn't forget Dilaudid."

Black Mollies?

"I looked it up," Edwards said. "A Black Molly is a highly intense form of methamphetamine."

McMillan has played characters in the throes of substance abuse before — such as Claire, an alcoholic, in Edward Albee's A Delicate Balance — but the Oklahoma matriarch of Letts' play is in a class all her own.

"There's a wee bit of Lady M in Violet," McMillan said, comparing Claire to Shakespeare's Lady Macbeth. "But I don't see her as a one-dimensional monster. You have to find something to love in a character, and Letts gives us plenty to love in this woman."

The daughters — played by Julie Rowe, Katherine Tanner and Meg Heimstead — have their own flaws.

"We ignored them to a certain extent," McMillan, in character as Violet, said to Edwards. "And their lives also have suffered. As grownups, they've taken on some of our characteristics."

"They keep trying, the daughters, they keep trying to understand, to connect," Edwards said. "They don't know how. And Violet doesn't have the capability to connect back to them anymore. She's not there for long enough periods of time to connect."

American Stage is producing August: Osage County not at its 182-seat home space, but a few blocks north at the Palladium Theater, which seats 849 and has a larger stage. Letts' script specifies that the Weston house has three stories. The play has a cast of 13 characters. There will be nine performances.

"I just felt like it was too big a work to paint on our small canvas here," said Todd Olson, artistic producing director of the company, who is directing the play. "And it was too big a payroll to keep around for five or six or seven weeks while we got through all our subscribers. And I didn't feel like passing on it was an option. I think this is the play of this generation, and I felt like if we had an opportunity to do it, it wouldn't be right to pass it up."

Olson has assembled a stellar group of actors for Letts' play. Casting began as long ago as last February.

"I felt like we needed to get the elder generation first," he said "Once Michael Edwards and Lisa McMillan signed on I kind of had an idea of where the family structure was going and what the sisters should look like."

McMillan, a New York actor, played another Violet at American Stage four years ago, Violet Venable, the smothering mother in Tennessee Williams' Suddenly Last Summer. (Trivia note: McMillan includes in her bio that she had a small part in a legendary Broadway flop, Moose Murders, which opened and closed on the same night in 1983.) Edwards starred as President Edward Smith in David Mamet's November last season at the theater.

Other cast members include Steve Garland, Brian Shea, Joe Parra, Wayne LeGette, Kerry Glamsch, Karel Wright and Sarah McAvoy. Tia Jemison plays the small but pivotal role of Johnna, an American Indian. "Johnna is the glue that holds it all together," Olson said. "She's the healthiest person in the play."

August: Osage County is often compared to the plays of Eugene O'Neill. In scope and impact, it is similar to Angels in America, Tony Kushner's two-part saga that was such a phenomenon in the 1990s. "To me it feels like Chekhov wrote a play with Sam Shepard," Olson said. "Katherine Tanner put it well. She said it feels like Tennessee Williams without the poetry."

Because August: Osage County is so long, including two intermissions, one of Olson's paramount concerns is pacing. "It would be easy to linger and chew the scenery, because there are so many occasions for really powerful emotional acting," he said. "It's important that the audience not get ahead of us and we always keep pushing forward."

The director also wants to bring out the dark comedy of Letts' play. "There is so much laughter," he said. "I just laugh out loud at some of the stuff he puts on the page. Some of it is so absurd, like the dinner scene that makes up most of Act 2. I don't know that there's another dinner scene like it in American theater."

McMillan and Edwards are relishing the opportunity to be in such a powerful work.

"Success, child-rearing, the Midwest — and everything possible that can go wrong in a family," McMillan said. "And the language Letts gives us is wonderful."

 Since its premiere in Chicago in 2007, August: Osage County has won a Pulitzer Prize, a Tony Award and a Drama Desk Award for best play.

 Deanna Dunagan, a onetime member of the Asolo Repertory Theatre in Sarasota, won the 2008 Tony for best actress for her performance as Violet Weston, the drug-addicted mother.

 It is one of the 10 most-produced plays around the country in the 2011-12 season.

 A movie starring Meryl Streep and Julia Roberts was announced, but production has been put on hold.

 Playwright Tracy Letts' father, Dennis Letts, originated the role of Beverly Weston, the family patriarch, in the Steppenwolf Theatre production in Chicago that went on to Broadway. The senior Letts, a college professor who came late to acting, taught at Southeastern Oklahoma State University. He died at 73 of lung cancer in 2008.